1. Field of the Invention
The present invention relates to an image processing apparatus and a method for controlling the image processing apparatus.
2. Description of the Related Art
When a user views an image by using an image display apparatus such as a television apparatus (hereinafter referred to as “television”), the image needs to be an easily viewed image quality depending on the ambient brightness or the lighting environment. For example, when the ambient area of a television screen is dark, an image becomes easy to view when the image is displayed with a reduced brightness. On the other hand, when the ambient area of a television screen is bright, an image becomes easy to view when the image is displayed with an increased brightness. This is not limited to the ambient brightness but is similarly applied to the color temperature surrounding a television screen. When the color temperature of the ambient area of a television screen is low, an image becomes easy to view when the image is also displayed with a decreased color temperature. On the other hand, when the color temperature of the ambient area of a television screen is high, an image becomes easy to view when the image is also displayed with an increased color temperature. Therefore, it is contemplated that the quality of an image displayed on a television screen be automatically adjusted depending on the brightness or color temperature surrounding the television screen.
However, a television is often used in a situation where the environment surrounding a television screen frequently changes. More specifically, a television may be used in the environment where the incidence of sunlight entering a room in which the television is installed may change, such as switching lighting, opening and closing a curtain, or the like. When image quality is automatically adjusted depending on brightness surrounding the television screen in the environment, the image quality of the television screen may be frequently switched following the frequent change in the surrounding environment, resulting in discomfort to the user.
Japanese Patent Laid-Open No. 2004-279503 discloses a technique in which the ambient illuminance of a television is detected to determine the display brightness of the television depending on the detected illuminance so that the display brightness is changed to the determined display brightness in a plurality of steps.
However, in the technique disclosed in Japanese Patent Laid-Open No. 2004-279503, the display brightness is changed in a plurality of steps. Consequently, when the ambient brightness is changed, it is time-consuming to switch an image to an optimum image quality. This produces the effect of reducing user discomfort caused by a sudden change in image quality. However, for example, when a user switches a channel to a movie program and intentionally dims an illumination immediately after the channel switching in order to make the image of the movie program easy to see, a problem occurs with the aforementioned technique. In such a case, the technique disclosed in Japanese Patent Laid-Open No. 2004-279503 requires time until an image can be displayed with the image quality adapted for dark illumination after a user has intentionally dimmed the illumination. In other words, regardless of the case where a user has intentionally changed the ambient brightness or color temperature or the case where a user has unintentionally changed the same, the technique disclosed in Japanese Patent Laid-Open No. 2004-279503 always changes the image step-by-step with a constant degree of change. With such a control, it is difficult to say that appropriate control corresponding to a user's intention is carried out.